1. Field of the Invention
The present invention relates to a stroke identifying unit. The stroke identifying unit is capable of working in conjunction with an electronic fuel injection controller of a four-stroke engine.
2. Description of the Relevant Art
In the background art, an electronic fuel injection controller for a four-stroke engine works in conjunction with a stroke identifier in order to properly time fuel injections for individual cylinders of the engine. The stroke identifier, of the background art, identifies the strokes of the individual cylinders on the basis of a relationship between a phase of a crankshaft, detected by a crank sensor, and a phase of a camshaft, detected by a cam sensor.
In order to detect the phase of the camshaft, the cam sensor has to be disposed in a cylinder head of the engine. The cylinder head has to be enlarged in order to accommodate the cam sensor. The cost of the cam sensor and the enlargement of the cylinder head increase the overall cost of the engine. Moreover, when the engine is used to power a motorcycle, the enlarged cylinder head is undesirable, since the engine of a motorcycle is subject to a height limitation.